The present invention is related to compound bows. In particular, the present invention provides a compound bow that is fully adjustable in draw length, draw weight and the percentage of dropoff from the maximum draw weight of the bow to the force required to hold the bowstring in the fully drawn position.
Compound bow structures permit the storage of energy in the bow structure thereby reducing the amount of force needed to hold the bowstring in the fully drawn position. The percentage of drop-off in the maximum draw weight of the bow to the force required to hold the bowstring in the fully drawn position is sometimes referred to as "let-off" For example, the archer draws the bowstring back with a force of 80 lbs. until a breakpoint is reached, and the force required to hold the bowstring drops to 40 lbs. once the breakpoint is passed which would correspond to a 50% let-off. As will be readily appreciated, a substantial percentage of let-off improves the archer's performance, for example, by permitting the archer to hold the bow steady in competition while aiming at the target. A high percentage of let-off also permits the hunter to maintain the bow in a "cocked" ready state for long periods of time while waiting for his quarry.
Compound bow structures have been disclosed that provided let-off through the use of eccentric wheels or pulleys. For example, U.S. Pat. No. 4,660,536 issued to Mcpherson discloses a compound archery bow system that employs a eccentric cam wheel having an elliptical or heart shaped cam slot. Generally, however, it is necessary to change the wheels or pulleys in such systems if one wants to change the draw weight, draw length or let-off of the bow, thereby requiring substantial disassembly of the components of the bow.
Disassembly of the bow reduces the archer's ability to quickly and easily make adjustments during competition or while in the field Accordingly, it would be desirable to provide a compound bow system wherein the draw weight, draw length and let-off of the bow would be fully adjustable without requiring disassembly.